The invention relates to the power force adjustment of a setting tool for driving fastening elements.
A wide range of fastening elements are driven from setting tools where the power force is supplied by explosive power or an air-gas mixture. Depending on the application, different setting power forces are required, for example, for fastening elements of different lengths. Different power forces can, for example, be obtained using cartridges of different strengths or with the help of a device that varies the power force output.
The regulation of the power force is accomplished, for example, by using a setting pin that controls the volume of the combustion chamber or the size of the open section of a release channel that connects the combustion chamber or the cartridge holder with the ambient atmosphere. Displacement of the setting pin in the axial direction is done, for example, using a cam disk that converts the rotary movement by the user into a rectilinear movement. With displacement of the setting pin, for example, the overall sectional dimension of the release channel is enlarged or decreased. The overpressure produced in the combustion chamber is vented to the ambient atmosphere through the release channel so that the acceleration of the piston is reduced, consequently reducing the setting power force.
In one setting tool known from the prior art, the adjustment wheel serving to regulate the power force is situated on the side of the setting tool housing. To prevent the wheel from turning on its own when the relevant accelerations and vibrations produced during the setting process act upon the setting tool, the adjustment wheel is biased against the inside wall of the setting tool by the action of a spring arranged between a cam disk and the adjustment wheel. A stud or lug projecting from the inside wall interacts in a form fitting manner with one of a plurality of grooves arranged on the adjustment wheel. Turning the adjustment wheel is only possible if the interlock is overcome by the axial displacement of the adjustment wheel counter to the force of the spring.
The primary object of the invention is to provide a setting tool with an adjustment wheel for regulating the power force that can be set quickly and securely, that is rotated easily and simply, and can be fixed in a desired position using a locking means. Moreover, the locking means itself and its function must be easily recognizable to the user.
In the setting tool according to the invention the locking means for the adjustment wheel is comprised of a two-armed lever that is arranged on the housing on a pivot and is easily accessible so that the adjustment wheel can be quickly released. Furthermore, the function of the lever is clearly and quickly recognizable.
The pivot axis of the lever extends preferably perpendicular to the axis of the adjustment wheel so that the lever can be pivoted in a plane that is arranged parallel to the adjustment wheel axis and is displaceable about its pivot axis.
To allow the pressure necessary for pivotal displacement of the lever to be applied in a direction running perpendicular to the setting direction, the axis around which the lever can be pivoted, is advantageously rotatable relative to the adjustment wheel.
To achieve automatic reset of the lever into a locking position, as soon as pressure application thereon is released, the lever is appropriately pivoted against the force of a spring out of a locking position and into a releasing position in which the adjustment wheel is freely rotatable.
To assure that accommodation of the spring requires as little space as possible, which ultimately affects the dimensions of the setting tool, it is preferably fashioned as a flat spring.
A particularly simplified form-locking connection is provided preferably by a detent arranged on the first lever arm of the lever, the detent extending into at least one of a plurality of form-fitting recesses arranged circumferentially on the adjustment wheel. The arrangement of the recesses at once provide the advantage that the adjustment wheel can more effectively be rotated by the user without the user""s fingers slipping off the adjustment wheel.
Particularly in narrow, hard-to-reach fastening sites it is advantageous if the lever in both its locking position and its releasing position does not protrude beyond the outside surface of the housing. Therefore, the lever is arranged in such a fashion that, in the releasing position, a second lever arm appropriately provided with a contact surface protrudes into a recess in the housing.